armour

Where it comes from

Armour ordinarily means protective covering worn in battle or placed around something vulnerable. Armour came through Old French armeure from Latin armatura, military equipment, based on arma, implements of war or weapons. Armoire came through French from Latin armarium, a cabinet for equipment and later books or valuables, also formed from arma. One branch of the arma family specialized in protective battle equipment; another named the cabinet in which equipment was kept and became a wardrobe.

How the meaning developed

Armour later expanded from the body to animals, ships, vehicles, cables, and figurative protection.